title: Exclusive MRI-based tandem and colpostats reconstruction in gynaecological brachytherapy treatment planning.
abstract: OBJECTIVE
  According to the GYN GEC-ESTRO Recommendations, MRI is needed with the modality of T2 weighted. CT-MR compatible tandem plus colpostats (T/C) (Nucletron) is widely used in cervical brachytherapy. The major challenge of MRI is the lack of dummy catheters. Therefore, an additional imaging modality is usually required. One disadvantage of sliced-based reconstruction is that resolution in longitudinal directions can be affected by the slice thickness. The aim of this study is to present a modified T/C applicator in which the catheter visibility is significantly improved.
  
  
  METHODS
  A modification to the existing T/C applicator has been made available, increasing the catheter entrance diameter. It allows a greater dummy catheter diameter, and consequently it can be filled with more material per unit length. Visibility was studied with different materials.
  
  
  RESULTS
  The catheter filled with saline water plus iodine compound was clearly seen in both axial and longitudinal acquisitions. To avoid uncertainties introduced by the slice thickness, a simple procedure is presented using longitudinal acquisitions.
  
  
  CONCLUSIONS
  The modified applicator plus catheter allows a powerful signal in T2 weighted MRI, using a very simple and accessible material. Also, a method is proposed to solve the problem of the uncertainty derived from slice thickness using few longitudinal acquisitions.
authors.affiliation: Radiotherapy Department, La Fe University Hospital, Valencia, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Perez-Calatayud
authors.forename: Frans
authors.initials: F
authors.lastname: Kuipers
authors.forename: Facundo
authors.initials: F
authors.lastname: Ballester
authors.forename: Domingo
authors.initials: D
authors.lastname: Granero
authors.forename: José
authors.initials: J
authors.lastname: Richart
authors.forename: Silvia
authors.initials: S
authors.lastname: Rodriguez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Tormo
authors.forename: Manuel
authors.initials: M
authors.lastname: Santos
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D002404:Catheterization; D005260:Female; D005833:Genital Neoplasms, Female / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted